The seven states sharing the Colorado River are considering a plan to protect Lake Powell by cutting the amount of water released downstream to Lake Mead, a Nevada water official said.

Under the plan, which could be implemented if drought persists through the winter, the amount of water released from Lake Powell, located on the Utah-Arizona border, would be reduced from 8.23 million acre-feet to 7.8 million acre-feet, Southern Nevada Water Authority General Manager Pat Mulroy said.

The nearly 9.5 percent reduction could help keep Lake Powell from shrinking further, jeopardizing power generation at Glen Canyon Dam. But it also could accelerate a drop in the water level downstream at Lake Mead, the primary water supply for Las Vegas, Mulroy said.

The reduction could prevent a "call on the river," requiring water users in the drought-stricken upper basin to give up more water to meet the 8.23 million acre-foot requirement set by existing water policy.

Mulroy said the plan was floated by representatives from the upper Colorado River Basin states of Colorado, Utah, New Mexico and Wyoming.

"Two more years of less than 50 percent runoff, and Powell's a dead pool," she said. "That's how close we are."

Don Oster, executive director of the Upper Colorado River Commission, called reducing the flow from Powell one option.

He said the upper basin's main proposal involved reviewing the operating plan for the river every six months instead of once a year during the drought.

"For us, the business-as-usual approach is not going to work any more," Oster said.

After five years of below-normal snowfall along the western slope of the Rocky Mountains, Lake Powell is at 40 percent of capacity and power generation at Glen Canyon Dam is down 40 percent. Lake Mead is at 54 percent of capacity.

If Lake Powell drops another 85 feet, generators will shut down, threatening supply and financial problems for utilities and their customers, officials said.

If Lake Mead drops 127 feet, power generation would be threatened and drinking water intakes would be exposed.

Mulroy said she expects an agreement before the end of the year on water levels at both reservoirs.

Bob Walsh, spokesman for the Bureau of Reclamation at Lake Mead, said "simple mathematics" show that cutting water releases from Lake Powell would affect Lake Mead unless there was a change in the amount of water released through Hoover Dam for delivery to Arizona, California and Mexico.

Excluding surplus water available in wet years, Arizona takes 2.8 million acre-feet of water from Colorado River annually. California gets 4.4 million acre-feet. Mexico gets 1.5 million acre-feet.

Nevada's annual allotment of Colorado River water is 300,000 acre-feet, with the Las Vegas Valley drawing 90 percent of all the water.

An acre-foot equals about 326,000 gallons, or enough to serve one and a half households in the Las Vegas area, according to Southern Nevada Water Authority figures.